Frenzy behind the scenes of a morning radio show.

It's 4:45 a.m., 15 minutes to air time. Outside the office tower in the middle of Bur.bank's Media District, Los Angeles is dark and silent.

Inside, it's pandemonium.

Rosemary Jimenez is ripping through photocopied lists of Associated Press stories, highlighting the titles of each one. "Grab your stuff and follow me," she tells a reporter whom she's enlisted to help with the pre-show prep. Before there's time to reply she's long gone, running at full flit down the hallway.

Things will not slow down from here.

Jimenez, 38, is the producer of the "Jamie, Frosty & Frank Show" on KYSR-FM 98.7, better known as Star 98. Every weekday morning she choreographs a four-hour call-in radio program that is a harrowing mix of planning and spontaneity.

Jimenez is in the production studio now, checking the satellite feed with Denver, where the show is simulcast by another station owned by Chancellor Media. Jimenez has to make sure that the studio clock is precisely synchronized with the one in Denver; otherwise, they'll go to commercial breaks at the wrong time.

At 4:52, Jimenez is sitting at her desk in the hallway just outside the studio, where she'll remain for the next four hours. The program will go on the air in eight minutes, and the hosts still aren't here.

"It's always crazy at this time - thinking, 'Oh my God, where are they?' "Jimenez says.

Frosty Stilwell rolls in at 4:54, looking a bit rumpled in a sweatshirt and jeans; on his heels is Frank Kramer. Last to arrive is Jamie White, clad in a black leather jacket and black slacks, who will provide the woman's perspective for the morning's discussions, which will focus on sex, move to innuendo, and then veer back to sex.

Inside the studio, Jimenez has given each jock a packet of clips: AP stories, interesting bits of news or lifestyle facts culled from women's magazines by a professional service, topical stories from the local papers, and a yellow sheet titled "Jamie's Discussion Topics," which White typed up after yesterday's show. They are things that she thinks would make for interesting conversation, like the fact that her husband can turn even the most innocuous remark into a sexual innuendo.

Just before 5 a.m., Jimenez sets the time delay. As night jock Bill Alexander signs off, Jimenez pushes a button that stretches the sound waves of his voice in a way that is barely noticeable to listeners. His speech is being slowed down, so that at the end of the process there is an eight-second delay between what he says and what is broadcast. (Delays on call-in shows are required by the Federal Communications Commission.)

The show begins. Jimenez, whose primary function is to screen calls, sits in front of a computer screen, a fax machine, a phone with seven lines and a wire-service printer. The phones start to light up. With each caller, Jimenez asks the same opening question: How old are you?

"We want people 18 and older. This is not a show for young children," she says. "I'm looking for people who can actually speak and are genuine fans."

During the course of the morning she will politely refuse dozens of kids, along with confused listeners who are unsure what they would like to talk about, people who want to tell lame jokes, and one obscene caller who asks Jimenez whether she is ticklish. Most of those calling from 5 a.m. to 7 a.m. live in Denver, where it's an hour later - or they're truck drivers with cell phones. The phones really light up after 7, when L.A. is waking up.

Jimenez has a computer program that creates a queue for each caller she clears for the air. On the screen, she has written a name and a brief description of what the caller wants to talk about; the hosts have a computer in the studio with the same information.

The pace is frantic. Jimenez has to keep up with the hosts, who sometimes move through callers faster than she can screen them. At the same time she's talking on the phone, she has to keep an ear open for what the hosts are saying because she's keeping a hand-written log to be used when she splices together "Best of..." shows to air on days that the hosts are on vacation. Meanwhile she's checking faxes, changing tapes and handling an array of other production chores.

It's 5:37, and White is wondering whether anyone has ever used Saran wrap as a condom. The phone lines explode.

"A Wonder bread bag?" Jimenez asks one caller. "Hold the line. Speak clearly and with lots of energy when they come on, OK?"

Quickly moving through the hallways is the only other member of the morning's production staff, a 25-year-old intern from Cal State Northridge named Marc Foster. It's his job to line up the "carts," or commercial cartridges, which are 30- or 60-second tapes of all the station's commercial messages. Foster has a master schedule of when each ad will run; he pulls them in order from a large rack and brings them to Stilwell, who runs the control panel inside the studio.

Foster, who wants to be a radio personality himself someday, is halfway through a three-month internship. He gets up at 3 a.m. to make the commute to Burbank from Simi Valley, then attends classes at Northridge, then works a part-time job in the evenings. He could use a shave.

"I work until 10 o'clock at night, then have to get up at 3 a.m.," Foster says. "What I do (for sleep) is like, get three hours here, four hours there. It's kind of getting old, but I'm going to make it."

Foster isn't the only one here living an odd life. The hosts will put in several hours after the show, planning the next day's program. How do they manage to stay funny and cheerful at 5 a.m.?

"About 20 of these," says White during a commercial break, pointing to a can of Diet Pepsi. "The first year I was really dragging, but now I'm used to it. It's just the body clock thing."

Jimenez, who arrived at 3:45 a.m., seldom leaves before 2 p.m. The first six hours of non-stop frenzy are fueled by her daily breakfast of a liquid vitamin drink, a bottle of water and a banana. After work she might go to the gym, then go home and watch the previous day's prime-time TV shows on video: she'll try to be in bed by 7 p.m.

"There are moments when you wake up and think, what am I doing? You're driving to work in the dark and thinking, no one knows I'm here," Jimenez says.

Odd hours and job stress prompted Jimenez to leave the "Mark & Brian Show" on KLOS-FM 95.5 early last year after an 11-year stint at the station. She spent a year traveling, getting back in touch with her own feelings - and sleeping a lot. She started her new job at Star 98 in February.

There is a feeling of detachment that comes with the early-morning shift. Jimenez is involved in the everyday world because that's part of her job - she must scan the newspapers, wire services and magazines to come up with interesting conversation topics for the hosts.

But she is divorced from a world most of us take for granted. She talks of watching a tape of the Grammy Awards on the Sunday following the Wednesday-night show, getting excited for each winner as if the show were live.

"It's surreal sometimes," Jimenez says. "Being right in it, but outside of it, you know?"